7.de5 is positionally inconsistent: e5 is Black's soft spot- he has managed to protect it blocking his own development, so it really does not make sense to release the tension by taking on e5. True, you get the bishop pair, but you lack development, and Black's knights have decent squares to occupy.

Why not simply 7.Bb3 with the idea increasing the pressure on e5 by Nbd2-Nc4? Stopping that with ...b5 allows the usual a2-a4 stuff.

You can also start with 7.Nbd2 I guess, since there are no ...Nxe4 or ...Na5 tricks. Even 7.Bd5!? Qe7 8.Nbd2 is a way to increase the pressure against e5.

@ chess608: You watch too many westerns. After 7.Bf4 ef4 8.e5 Be7 9.ef6 Bxf6 10.Re1+ Ne7 Black will castle comfortably, and while white will be trying getting back that pawn on f4, play ...d5 and make good use of his bishop pair.